<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Dom
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */

/**
 * Transform CSS selectors to XPath
 *
 * @package    Zend_Dom
 * @subpackage Query
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: Css2Xpath.php 17293 2009-07-30 02:34:37Z yoshida@zend.co.jp $
 */
class Zend_Dom_Query_Css2Xpath
{
	/**
	 * Transform CSS expression to XPath
	 *
	 * @param  string $path
	 * @return string|array
	 */
	public static function transform($path)
	{
		$path = (string) $path;
		if (strstr($path, ',')) {
			$paths       = explode(',', $path);
			$expressions = array();
			foreach ($paths as $path) {
				$xpath = self::transform(trim($path));
				if (is_string($xpath)) {
					$expressions[] = $xpath;
				} elseif (is_array($xpath)) {
					$expressions = array_merge($expressions, $xpath);
				}
			}
			return $expressions;
		}

		$paths    = array('//');
		$segments = preg_split('/\s+/', $path);
		foreach ($segments as $key => $segment) {
			$pathSegment = self::_tokenize($segment);
			if (0 == $key) {
				if (0 === strpos($pathSegment, '[contains(@class')) {
					$paths[0] .= '*' . $pathSegment;
				} else {
					$paths[0] .= $pathSegment;
				}
				continue;
			}
			if (0 === strpos($pathSegment, '[contains(@class')) {
				foreach ($paths as $key => $xpath) {
					$paths[$key] .= '//*' . $pathSegment;
					$paths[]      = $xpath . $pathSegment;
				}
			} else {
				foreach ($paths as $key => $xpath) {
					$paths[$key] .= '//' . $pathSegment;
				}
			}
		}

		if (1 == count($paths)) {
			return $paths[0];
		}
		return implode(' | ', $paths);
	}

	/**
	 * Tokenize CSS expressions to XPath
	 *
	 * @param  string $expression
	 * @return string
	 */
	protected static function _tokenize($expression)
	{
		// Child selectors
		$expression = str_replace('>', '/', $expression);

		// IDs
		$expression = preg_replace('|#([a-z][a-z0-9_-]*)|i', '[@id=\'$1\']', $expression);
		$expression = preg_replace('|(?<![a-z0-9_-])(\[@id=)|i', '*$1', $expression);

		// arbitrary attribute strict equality
		if (preg_match('|([a-z]+)\[([a-z0-9_-]+)=[\'"]([^\'"]+)[\'"]\]|i', $expression)) {
			$expression = preg_replace_callback(
                '|([a-z]+)\[([a-z0-9_-]+)=[\'"]([^\'"]+)[\'"]\]|i',
			create_function(
                    '$matches',
                    'return $matches[1] . "[@" . strtolower($matches[2]) . "=\'" . $matches[3] . "\']";'
                    ),
                    $expression
                    );
		}

		// arbitrary attribute contains full word
		if (preg_match('|([a-z]+)\[([a-z0-9_-]+)~=[\'"]([^\'"]+)[\'"]\]|i', $expression)) {
			$expression = preg_replace_callback(
                '|([a-z]+)\[([a-z0-9_-]+)~=[\'"]([^\'"]+)[\'"]\]|i',
			create_function(
                    '$matches',
                    'return $matches[1] . "[contains(@" . strtolower($matches[2]) . ", \' $matches[3] \')]";'
                    ),
                    $expression
                    );
		}

		// arbitrary attribute contains specified content
		if (preg_match('|([a-z]+)\[([a-z0-9_-]+)\*=[\'"]([^\'"]+)[\'"]\]|i', $expression)) {
			$expression = preg_replace_callback(
                '|([a-z]+)\[([a-z0-9_-]+)\*=[\'"]([^\'"]+)[\'"]\]|i',
			create_function(
                    '$matches',
                    'return $matches[1] . "[contains(@" . strtolower($matches[2]) . ", \'" . $matches[3] . "\')]";'
                    ),
                    $expression
                    );
		}

		// Classes
		$expression = preg_replace('|\.([a-z][a-z0-9_-]*)|i', "[contains(@class, ' \$1 ')]", $expression);

		return $expression;
	}
}
